At the present time there is a constantly increasing demand for shellfish. Shellfish are not only used as seafood for consumption by humans, but are also in constant demand for the shells themselves. The value of, and the demand for these shells are constantly increasing. The shells are utilized in various technologies, such as for making lime which is employed as fertilizer, poultry grit, road surfaces (commonly in place of gravel), ballast for railroad track beds, etc.
While this invention has application for all shellfish, the use of the invention to foster oyster beds is emphasized herein for purposes of illustration.
This demand for oysters and their shells in this country has made the development of new oyster beds an attractive commercial venture. To date, the oyster industry has depended upon the collection of oyster larvae, known as "spat", on various natural underwater materials to which the spat attach themselves to promote new oyster growth. These underwater materials are known as cultch. The cultch material is distributed on exiting oyester beds or in new locations to start new oyster beds. The oysters are allowed to develop in these beds and are subsequently harvested when they reach a suitable size.
The selection of the clutch, which as stated, provides attachment points for the oyster spat, is of course important to the optimum development of the oyster beds. The spat must have cultch to attach to in order to mature.
A major factor in the selection of the cultch material is its ability to attract the oyster spat. Thus, the cultch material selected should remain where it is placed and not drift away in underwater currents or during storms. It is also desirable that the cultch resist sinking in sand or mud, otherwise, the spat would suffocate from the sediment deposits and die. Another consideration is that the cultch material is preferably non-corrosive so that it can be reused a number of times.
It is also important that the material chosen as cultch be resistant to the formation of slime thereon when placed on the oyster bed. The spat will reject the cultch if slime should form on its surface. Another factor in the selection of the cultch material is the ease with which the oysters can be removed from the cultch at harvest.
Cultch for oyster spat takes many forms of which oyster shells themselves are one of the most popular. However, the supply of oyster shells is not sufficiently abundent to meet this demand and the use of oyster shells as cultch is not economically feasible, due in part to the value of the shells for use in other technologies as discussed above. Alternatively, other materials have been used such as stones, bamboo, tiles, tarred ropes, tire rings, etc.
Examples of these prior attempts to form artificial cultch are disclosed in U.S. Pat. No. 611,199 to Hendryx, U.S. Pat. No. 1,921,945 to Robertson, U.S. Pat. No. 2,319,170 to Toner, U.S. Pat. No. 3,298,354 to Geer, U.S. Pat. No. 3,347,210 to Golub, U.S. Pat. No. 3,430,607 to Derouen, U.S. Pat. No. 3,455,278 to Hunt, U.S. Pat. No. 3,556,052 to Blount, U.S. Pat. No. 3,572,292 to Quayle et al, U.S. Pat. No. 3,685,490 to Adams, U.S. Pat. No. 3,701,338 to McMillin, U.S. Pat. No. 3,738,318 to Woodbridge et al and U.S. Pat. No. 4,196,694 to Buchanan.
However, these prior artificial cultch materials do not satisfy all the optimum criteria for cultch discussed above. Therefore, there exists a need in the art for a method of fostering an oyster bed which results in increased production of oysters from the bed. This invention addresses this need in the art, as well as other needs which will become apparent to those skilled in the art once given this disclosure.